With the law taking effect on Jan. 1, 2015, producers can't afford to wait any longer to begin construction on new hen enclosures, said Dale Stern, ACEF's Sacramento-based attorney.

Growers don't want to make a multi-million-dollar investment in new housing systems that could end up being considered illegal, he argues.

"This is really the last shot we've got," said Stern, who handles food and agriculture cases for Downey Brand LLP.

The law's lack of clarity about enclosure standards has become dire because new facilities will require an investment of more than $400 million by the state's egg farmers and an estimated three years to build, the Sacramento-based ACEF said in a news release.

The egg farmers' group maintains it decided to sue after the state Department of Food and Agriculture commissioned a study at the University of California-Davis that concluded the law is unclear.

The initiative sponsored by the Humane Society of the United States was intended to free chickens from the cramped, bare-wire cages used by many producers. The law says chickens must be able to stand and stretch their wings and engage in other natural behaviors.

The legal action comes after a federal judge in August upheld the law.

"You can't keep filing the same claim over and over again hoping for a different result," HSUS attorney Jonathan Lovvorn told The Associated Press. "A federal judge was walked through the arguments and said it doesn't take Columbo to figure out what this law means. They're judge shopping."

The animal welfare group and United Egg Producers teamed up this year to sponsor congressional legislation that would set a national standard of 125 square inches of space for each chicken. California producers would have to adhere to the standard by 2015. The ACEF supports the legislation.